Gamma Radioactivity in Some Components of the Boka Kotorska Bay Environment

Cs-137 and some naturally occurring gamma-emitters (K-40, as well as Ra-226 and Th-232) in samples of different nature from the Boka Kotorska Bay in Montenegro were measured by standard HPGe spectrometry. Samples, including surface seawater, sea grass Posidonia oceanica, mullet species Liza aurata and Liza ramada - whole individuals and some organs, as well as soil and sand from the coast, have been analyzed to establish baselines for that part of the South Adriatic Sea marine environment. In soil, Cs-137, K-40, Ra-226 and Th-232 activity was found to be 15.94, 646.04, 22.09 and 48.03 Bq kg-1 respectively, while in sand - 0.27, 21.67, 6.59 and 1.33 Bq kg-1 respectively. An average K-40, Ra-226 and Th-232 activity in P. oceanica was 476.22, 2.95 and 0.34 Bq kg-1, respectively, while Cs-137 was detected in amount of 2.31 Bq kg-1. Cesium and radium in seawater were < 0.05 and 0.13 Bq L-1, respectively, while potassium - 0.66 Bq L-1, and thorium - 0.19 Bq L-1. Radioactivity in L. aurata is found to be higher than in L. ramada. Annual intake of gamma emitting radionuclides by human consumers of L. aurata is estimated to provide an effective dose of about 0.05 mSv y-1, which is a small fraction (2%) of average annual effective dose due to exposure to natural radiation sources, and somewhat higher fraction (5%) of the public dose limit (1 mSv). Annual intake by consuming L. ramada has been estimated to be lower (0.008 mSv y-1), i.e., smaller fraction of natural background (0.33%). (Author)